Determining Distances Between Broadcasting Devices and Receiving Devices

The present application is a continuation application of U.S. Non-Provisional application Ser. No. 17/342,371 filed on Jun. 8, 2021, which claims the benefit of U.S. Provisional Patent Application No. 63/127,922, filed on Dec. 18, 2020. The disclosure of the above-referenced application is hereby incorporated by reference in its entirety.

Computing devices and/or electronic devices often communicate with each other using communication networks. These communication networks may use different network or communication protocols. One such network or communication protocol may be Bluetooth. Various devices may establish connections with each other and communicate data (e.g., transmit and/or receive data) with each other using the Bluetooth protocol.

As discussed above, various devices (e.g., computing devices) may establish connections with each other and communicate data (e.g., transmit and/or receive data) using the Bluetooth protocol. One version or type of the Bluetooth protocol may be the Bluetooth Low Energy (LE) protocol. As more and more devices are included in or join a communication network, it may be useful to determine the distance and/or position of these various devices. There are many applications and/or uses for determining the distance/position of these various devices. For example, it may be useful to track the positions/locations of robots in warehouse, of fans in a concert, of customers' cart in the shopping centers, of drones, of passengers at an entrance gate, of passengers in or around a bus/train.

A round trip time (RTT) of messages may be used to track the position and/or locations of devices. Often, a direct or dedicated connection may be established between two devices, to determine the distance between the two devices based on the RTT. This may use more network resources of a communication network (e.g., timeslots, frequencies, etc.). In addition, the messages used to determine the RTT are often not secure. This may allow malicious users or devices to intercept these messages and masquerade as devices on the network, or to use the RTT for their own purposes. Thus, it may be useful to allow a device to determine the distance to another device without using a direct/dedicated connection. It may also be useful to determine the distance to the other device in a more safe and/or secure manner.

Reference in the description to “an embodiment,” “one embodiment,” “an example embodiment,” “some embodiments,” and “various embodiments” means that a particular feature, structure, step, operation, or characteristic described in connection with the embodiment(s) is included in at least one embodiment of the disclosure. Further, the appearances of the phrases “an embodiment,” “one embodiment,” “an example embodiment,” “some embodiments,” and “various embodiments” in various places in the description do not necessarily all refer to the same embodiment(s).

The description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show illustrations in accordance with exemplary embodiments. These embodiments, which may also be referred to herein as “examples,” are described in enough detail to enable those skilled in the art to practice the embodiments of the claimed subject matter described herein. The embodiments may be combined, other embodiments may be utilized, or structural, logical, and electrical changes may be made without departing from the scope and spirit of the claimed subject matter. It should be understood that the embodiments described herein are not intended to limit the scope of the subject matter but rather to enable one skilled in the art to practice, make, and/or use the subject matter.

is a block diagram illustrating an example communication networkaccording to one or more embodiments. The communication networkincludes a broadcasting device B, receiving device R, receiving device R, receiving device R, receiving device R, receiving device R, receiving device R, receiving device R, receiving device R, receiving device R, receiving device R, receiving device R, and receiving device R. A broadcasting device may be any device that is capable of wireless communications (e.g., capable of transmitting and/or receiving data via a wireless transmission medium, such as radio-frequency signals). A receiving device may also be any device that is capable of wireless communications. The communication networkmay allow the receiving devices Rthrough Rto communicate data (e.g., transmit and/or receive data) with the broadcasting device B. The communication networkmay also allow the receiving devices Rthrough Rto communicate data between each other (e.g., Rmay communicate data with R, Rmay communicate data with R, etc.).

In one embodiment the communication networkmay be a Bluetooth network. A Bluetooth network may be a network where the devices (e.g., broadcasting device Band receiving devices Rthrough R) communicate data using the Bluetooth protocol. In some embodiments, the Bluetooth network may be a Bluetooth Low Energy (LE) network (e.g., a network that uses the Bluetooth LE protocol). The broadcasting devices Band the receiving devices Rthrough Rmay be computing devices. A computing devices may be may be any device, machine, or apparatus that is capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that device. A computing device may include a processing device (e.g., one or more of a processor, a central processing unit (CPU), a processing core, etc.), a memory (e.g., flash memory, a hard disk, random access memory, etc.) and/or other components/devices. Examples of a computing device may include, but are not limited to Internet-of-Things (IoT) devices, computers (e.g., laptop computers, desktop computers, server computers table computers), cellular devices (e.g., smartphones, a cell phone, etc.), smart home devices, wearable devices (e.g., smartwatches), a tracking device, tracking tags, a Bluetooth tag, etc.

In one embodiment, the broadcasting device Bmay broadcast (e.g., transmit) an advertising message to the receiving devices Rthrough Rand/or to other devices that are part of the communication network. An advertising message may be any message, packet, frame, etc., that is transmitted on a network and that is received by one or more other devices on the network. The advertising messages and/or response messages may be used by the broadcasting devices and/or receiving devices Rthrough Rto communicate data via a common communication channel (e.g., a shared communication channel, an advertising channel, etc.).

As discussed above, the communication networkmay be a Bluetooth network (e.g., a Bluetooth LE network). In one embodiment, the advertising message may be a AUX_SYNC_IND message/packet. In another embodiment, the advertising message may be a NEW_ADVERTISEMENT message/packet or any other message (e.g., a broadcasted message) that indicates an advertisement.

In one embodiment, the broadcasting device Bmay receive a set of response messages (e.g., a plurality of response messages) from one or more of the receiving devices Rthrough R, based on the advertising message (e.g., the broadcast message). For example, after receiving the advertising message (broadcasted/transmitted by the broadcasting device B), each of the receiving devices Rthrough Rmay responsively transmit a response message to the broadcasting device B.

In one embodiment, the response message (transmitted by any one of receiving devices Rthrough R) may be a Bluetooth RSP_PACKET message/packet.

In one embodiment, the advertising messages (e.g., broadcast messages) and/or the response messages may be connectionless communications. For example, the broadcasting device Band the receiving devices Rthrough Rmay communicate advertising messages and/or the response messages without establishing direct connections and/or communication channels with each other. Thus, the exchange of advertising messages and/or response messages may be a connectionless exchange (e.g. Bluetooth LE connectionless mode).

In another embodiment, the advertising messages and/or the response messages communicated may be communicated (e.g., transmitted and/or received) via an advertising communication channel. The advertising communication channel may be a shared or common communication channel that is used by multiple devices, such as the broadcasting device Band the receiving devices Rthrough R. The use of a shared or common channel may allow the broadcasting device Band the receiving devices Rthrough Rto communicate the advertising/response messages without establishing direct/dedicated connections (e.g., may allow for connectionless communications).

In one embodiment, the response messages transmitted by the receiving devices Rthrough Rmay include data (e.g., first data) that allows the broadcasting device to determine, estimate, approximate, etc., a distance between the receiving devices Rthrough R. For example, the response message received from receiving device Rmay include a time of arrival, a time of departure, and/or a difference between the time or arrival and time of departure that is used by the broadcasting device Bto determine or estimate the distance between the broadcasting device Band receiving device R. For example, a response message transmitted by receiving device Rmay include data (e.g., first data) that may indicate one or more of when the receiving device Rreceived the advertising message from the broadcasting device B, when the receiving device Rtransmitted the response message.

In one embodiment, the data that allows or is used by the broadcasting device Bto determine/estimate the distance (between the broadcasting device Band a receiving device) may be included in a payload portion (e.g., a protocol data unit) of a response message, as discussed in more detail below.

In one embodiment, the response message may also include data that is used by the broadcasting device Bto determine the angle of arrival (AoA) and/or the angle of departure (AoD) of various messages/packets, such as the response messages and the advertising messages. For example, the response message may include additional data that indicates the AoA of an advertising message received from the broadcasting device B. This may allow the broadcasting device to determine both a relative elevation and/or position of a receiving device. For example, the additional data may allow the broadcasting device Bto determine whether receiving device Ris above, below, to the left, or to the right of the broadcasting device B.

In one embodiment, the broadcasting device Bmay determine a set of distances between the broadcasting device Band the receiving devices Rthrough Rbased on the response messages. For example, based on a time when the advertising message was received by each receiving device, a time when each receiving device transmitted the response message, and/or a difference between the two times, the broadcasting device Bmay determine/estimate a distance between the broadcasting device Band each receiving device (e.g., by determining an RTT for broadcast/response messages).

In one embodiment, the advertising messages and the receiving messages may be communicated between the broadcasting device Band the receiving devise Rthrough Rbased on an advertisement interval. The advertisement interval may also be referred to as a broadcast interval. The advertisement interval may be divided into sub-intervals (e.g., advertisement sub-intervals). The sub-intervals may be divided into timeslots. At the first timeslot of each sub-interval, the broadcasting device may broadcast/transmit the advertising message. Each subsequent timeslot in the sub-interval may be associated with one of the receiving devices Rthrough R, as discussed in more detail below. The assignment and/or association of different receiving devices to different timeslots may be performed during an initial process (e.g., a registration process, an initiation process, a provisioning process, a setup process, etc.).

In one embodiment, a receiving device (e.g., one or more receiving devices Rthrough R) may receive an advertising message transmitted by the broadcasting device B. The receiving device may transmit a response message based on or in response to the advertising message. The receiving device may transmit the response message during an assigned timeslot of a sub-interval of an advertisement period, as discussed in more detail below.

As discussed above, the advertising messages and the response messages are used by the communication network for various purposes. By piggybacking the data/information that is used to determine the distance (e.g., the first data, a difference between a time or departure and a time of arrival, etc.) in other types of messages, the resources and/or bandwidth used by the communication networkmay be reduced. This may help reduce the amount of network resources used by the communication network. In addition, the data that is used to determine the distances (e.g., the first data) may be encrypted to prevent malicious users from masquerading as devices in the communication network. This may improve the security of the communication network.

shows an example timing diagramillustrating transmission and reception of messages by different devices according to one or more embodiments. The timing diagramincludes broadcasting device Band receiving devices Rthrough R(illustrated). As discussed above, the broadcasting device Bmay transmit (e.g., broadcast) an advertising message to the receiving devices Rthough R. Each of the receiving devices Rthough Rmay transmit a response message to the broadcasting device B.

The broadcasting device Bmay determine a round trip time (RTT) for each receiving device Rthrough R, as discussed in more detail below. The RTT for a receiving device may be the sum of the time of flight (ToF) for the advertising message to reach a receiving device (e.g., the amount of time over the air it takes for the broadcasting device's radio-frequency signal to reach the receiving device) and the ToF for the response message to reach the broadcasting device (e.g., the amount of time over the air it takes for the receiving device's radio-frequency signal to reach the broadcasting device). For example, the RTT may be 2*ToF. The RTT may be used to determine or estimate the distance between the broadcasting device and the receiving device. For example, the distance between the broadcasting device and the receiving device may be determined based on the RTT and the speed that the associated radio-frequency signals (e.g., messages, packets, frames, etc.) travel through a wireless transmission medium (e.g., the speed of light).

Timing diagramillustrates the times when the broadcasting device Btransmits an advertising message and receives response messages from the receiving devices Rthrough R. The broadcasting device transmits the advertising message at time ToD(e.g., a time of departure). Receiving device Rreceives the advertising message time ToA, receiving device Rreceives the advertising message time ToA, and receiving device Rreceives the advertising message time ToA. Receiving device Rtransmits a response message at time ToD, receiving device Rtransmits a response message at time ToD, and receiving device Rtransmits a response message at time ToD. Broadcasting device Breceives the response from receiving device Rat time ToA, receives the response from receiving device Rat time ToA, and receives the response from receiving device Rat time ToA.

In one embodiment, the round trip time (RTT) to transmit a broadcast message and receive the response message from any receiving device X may be determined based on equation (1) below.

Thus (based on equation (1)), the round trip times RTT, RTT, and RTT, may be determined using equations (2) through (4) below.

is an example timing diagramillustrating transmission of messages by different devices according to one or more embodiments. As discussed above (in conjunction with), a communication network (e.g., communication network) may include a broadcasting device Band receiving devices Rthrough R. The broadcasting devices may broadcast advertising messages (e.g., broadcast messages) to the receiving devices Rthrough Rand the receiving devices may transmit response messages to the broadcasting devices (in response to the advertising messages).

As illustrated in, the timing diagramillustrates an advertisement interval (e.g., a Bluetooth advertisement interval) during which the broadcasting device Bmay transmit one or more advertising messages and during which the receiving devices Rthrough Rmay transmit one or more response messages.

The advertisement intervalis divided into four sub-intervals, sub-intervalsthrough. Each sub-interval includes timeslotsthrough. The broadcasting device Bmay transmit an advertising message (e.g., an AUX_SYNC_IND packet, a NEW_ADVERTISEMENT packet, etc.) during the timeslotof each sub-interval. For example, the AUX_SYNC_IND packet may be transmitted at the beginning of the first sub-intervalin the advertisement interval. The NEW_ADVERTISEMENT packet (rather than the AUX_SYNC_IND packet) may be transmitted at the beginning of each of the remaining sub-intervalsthroughin the advertisement interval. Each of the receiving devices is assigned or associated with one of the timeslotsthrough. For example, receiving device Ris associated with or assigned timeslotin sub-interval. In another example, receiving device Ris associated with or assigned timeslotin sub-interval. Different groups or subsets of receiving devices may be associated with timeslots for different sub-intervals. For example, receiving devices Rthrough Rare associated with or assigned timeslots in sub-interval. As illustrated in, each of the receiving devices Rthrough Rmay transmit a response message at the associated timeslot. For example, Rtransmits a response message at time slotin sub-interval, Rtransmits a response message at timeslotin sub-interval, etc.

In one embodiment, the broadcasting device Bmay assign or associate each receiving device with a timeslot in a sub-interval during an initial process (e.g., a registration process, an initiation process, a provisioning process, a setup process, etc.). For example, each receiving device may initially communicate with the broadcasting device Bvia a dedicated communication channel. The broadcasting device Bmay transmit a message to the receiving device indicating which timeslot and which sub-interval has been assigned to the receiving device.

In one embodiment, each response message is transmitted (by a respective receiving device) and/or received by the broadcasting device Bwithin a predetermined period of time (e.g., before a predetermined period of time has expired). For example, the response messages from the receiving devices Rthrough Rmay be received before sub-intervalstarts (e.g., received within the period of time for the sub-interval). In another example, the response messages from the receiving devices Rthrough Rmay be received before sub-intervalstarts (e.g., received within the period of time for the sub-interval). In further example, the response messages for the receiving devices Rthrough Rmay be received by the end of the timeslot when the respective receiving device transmitted the response message (e.g., the response message transmitted by receiving device Ris received by the broadcasting device Bbefore the end of timeslot.).

shows example timing diagrams,,, andillustrating transmission and reception of messages by different devices according to one or more embodiments. As discussed above (in conjunction with), a communication network (e.g., communication network) may include a broadcasting device Band receiving devices Rthrough R. The broadcasting devices may broadcast advertising messages (e.g., broadcast messages) to the receiving devices Rthrough Rand the receiving devices may transmit response messages to the broadcasting devices (in response to the advertising messages). Although there are a total of thirteen devices illustrated in, the timing diagramsthroughillustrated incorrespond to broadcasting device B, receiving device R, receiving device R, and receiving device R. For example, the timing diagramsthroughillustrated incorrespond to sub-interval.

Timing diagramillustrates the times when the broadcasting device Btransmit an advertising message and receives response messages. The broadcasting device transmits the advertising message at time ToD(e.g., a time of departure) in time slot. The first response message from receiving device Ris received at time ToA(e.g., a time of arrival). The second response message from receiving device Ris received at time ToA. The third response message from receiving device Ris received at time ToA.

Timing diagramillustrates the times when the receiving device Rreceives the advertising message and transmits a response message. The receiving device Rreceives the advertising message at block ToAand transmits the response message at time ToD. As discussed above, the response message may include data that indicates one or more of the time ToD, time ToA, and a difference between time ToDand time ToA.

Timing diagramillustrates the times when the receiving device Rreceives the advertising message and transmits a response message. The receiving device Rreceives the advertising message at block ToAand transmits the response message at time ToD. As discussed above, the response message may include data that indicates one or more of the time ToDand time ToA, and a difference between time ToDand time ToA.

Timing diagramillustrates the times when the receiving devicereceives the advertising message and transmits a response message. The receiving device Rreceives the advertising message at block ToAand transmits the response message at time ToD. As discussed above, the response message may include data that indicates one or more of the time ToDand time ToA, and a difference between time ToDand time ToA.

As discussed above, the RTT (e.g., the ToF for the advertising message and the ToF for the response message) may be determined based on equation (1) described herein.

The RTT for a receiving device may be used to determine or estimate the distance between the broadcasting device and the receiving device (e.g., based on RTT and the speed of light).

is a block diagram illustrating example messages that may be transmitted and received in a communication network. As discussed above, the communication network may be a Bluetooth network, such as a Bluetooth LE network. The communication network may include one or more broadcasting devices (e.g., broadcasters, beacons, etc.) and may include one or more receiving devices (e.g., Bluetooth devices, Bluetooth tags, etc.). The broadcasting device may broadcast (e.g., transmit) advertising messages (e.g., broadcast messages) and the receiving devices may transmit responses messages, as discussed above.

As discussed above, one type of advertising message may be an AUX_SYNC_IND packet/message. Another type of advertising message may be a NEW_ADVERTISEMENT packet/message. As illustrated in, advertising messages such as the AUX_SYNC_IND packet and the NEW_ADVERTISEMENT packet may have the same format. The advertising message includes a preamble (which may be 1-2 octets), an access address (which may be four octets), and a protocol data unit (PDU). The access address may allow a receiving device to determine a more precise time when an advertising message was received by the receiving device. The size/length of the PDU may vary in different types of advertisements (e.g., different types of advertising messages). The advertising message may also include cyclic redundancy check bits (CRC). In one embodiment, the advertising message may optionally include a constant tone extension (CTE). The CTE may include optional data which may be used to determine the AOA and/or AOD of a message. For example, the CTE may include angular data/information as specified in the Bluetooth Core Specification.

Also as discussed above, one type of response message may be a Bluetooth RSP_PACKET packet/message. As illustrated in, a response message such the RSP_PACKET packet includes a preamble (which may be 1-2 octets), an access address (which may be four octets), and a protocol data unit (PDU). The size/length of the PDU may vary in different embodiments. The response message may also include a cyclic redundancy check bits (CRC). In one embodiment, the response message may optionally include a constant tone extension (CTE). The CTE may include optional and/or additional data which may be used to determine the AoA and/or AoD of a message.

As discussed above, the RSP_PACKET may include the data used by the broadcasting device to determine the distance between the broadcasting device and a receiving device. For example, the RSP_PACKET may include an access address that may be used by a broadcasting device to determine a time when a response message was received by the broadcasting device. The access address may be generated in a secure manner. For example, the access address may be generated using a block cipher, an encryption algorithm, a hashing algorithm, etc.

In one embodiment, the access address may be generated or determined (by a broadcasting device or a receiving device) using a deterministic random bit generator (DRBG), which in turn uses a block cipher, such as an Advanced Encryption Standard (AES) 128-bit block cipher. The block cipher may use a security function that accepts a key and a nonce vector. The key and the nonce vector may be provisioned, instantiated, etc., prior to communicating the advertising messages and the response messages. For example, the key and the nonce vector may be shared between the broadcasting device and the receiving device. The nonce vector may be incremented each time a message is transmitted. For example, each time a broadcasting device transmits an advertising message or a receiving device transmits a response message, it may increment its respective nonce vector.

In one embodiment, each time a broadcasting device transmits an advertising message, it may generate a new and/or different access address. This may make it more difficult for malicious devices or uses to pretend that they are also a broadcasting device and may prevent a man in the middle (MITM) attack. The receiving devices that receive the broadcasting device may be able to verify the access address using the key and the nonce vector that were provisioned or exchanged between the broadcasting device and the receiving devices.

In one embodiment, each time a receiving device transmits a response message, it may generate a new and/or different access address. For example, when a receiving device includes the data (e.g., one or more of a first time when an advertising message was received by a receiving device, a second time when a response message was transmitted by the receiving device, and a difference between the first time and the second time), the receiving device may encrypt, encipher, etc., the data using the block cipher to generate the access address. This may make it more difficult for malicious devices or users to pretend that they are also a receiving devices and may prevent a man in the middle (MITM) attack.

In one embodiment, the access address allows the RTT and/or the distance between the broadcasting devices to be determined more precisely and/or accurately. For example, the access address may allow the broadcasting device to determine a more precise time (e.g., a time with a higher resolution) when the response message was received by the broadcasting device, as discussed in more detail below.

is a block diagram illustrating example messages that may be transmitted and received in a communication network. The messages may be examples of advertising/broadcast messages and response messages. The portions/fields of the messages may be similar to the portions/fields described above in. The advertising message (e.g., AUX_SYNC_IND/NEW_ADVERTISEMENT) includes a preamble (which may be 1-2 octets), an access address (which may be four octets and is known by both the transmitting device and the receiving device), and a protocol data unit (PDU). The advertising message may also include a cyclic redundancy check bits (CRC). In one embodiment, optional and/or additional data (which may be used to determine the AoA and/or AoD of a message) may be included as part of the PDU.

The response message (e.g., RSP_PACKET packet) includes a preamble (which may be 1-2 octets), an access address (which may be four octets), and a protocol data unit (PDU). The size/length of the PDU may vary in different embodiments. The response message may also include a cyclic redundancy check bits (CRC). In one embodiment, the additional data (which may be used to determine the AoA and/or AoD of a message) may be included in the PDU.